What is the minimum capacity requirement for the secondary power supply for the protected premises system under quiescent load?

What is the minimum capacity requirement for the secondary power supply for the protected premises system under quiescent load?

• A. 12 hours
• B. 48 hours
• C. 72 hours
• D. 24 hours

Answer: (D)

The backup power for a protected premises fire alarm system must be able to sustain normal, standby operation during a power outage. Quiescent load refers to the system’s standby current when no alarms are active, so the secondary power supply must provide enough energy to keep the system monitoring and ready for at least 24 hours at that standby draw. This 24-hour requirement ensures the system remains functional through a power outage for a full day, until power is restored or another supply is arranged. Shorter durations like 12 hours wouldn’t meet the standard, while longer durations such as 48 or 72 hours go beyond the minimum need for protected premises.

The backup power for a protected premises fire alarm system must be able to sustain normal, standby operation during a power outage. Quiescent load refers to the system’s standby current when no alarms are active, so the secondary power supply must provide enough energy to keep the system monitoring and ready for at least 24 hours at that standby draw. This 24-hour requirement ensures the system remains functional through a power outage for a full day, until power is restored or another supply is arranged. Shorter durations like 12 hours wouldn’t meet the standard, while longer durations such as 48 or 72 hours go beyond the minimum need for protected premises.